1. Technical Field
The present disclosure relates to a self-venting cannula assembly. More particularly, the present disclosure relates to a self-venting cannula assembly including a filter element.
2. Background
Liquid medications for injection and intravenous applications are commonly available in rigid containers sealed with an elastomeric septum. Typically, the amount of liquid medication in these containers is in excess of the amount required for an individual dose. It is therefore often necessary for a medical professional to transfer the liquid medication from one container to another, such as I.V. bottles or to other storage or delivery devices such as syringes. Transfer of liquid medication from one container to another is also common in instances in which the medication has a short shelf life and reconstituted or mixed with a diluents just prior administration to a patient. The diluent may be for example a dextrose solution, a saline solution or even water. Transfer of liquid medication to and from these vials involves piercing the septum to provide a path for the medication and also to provide a path for air to escape or enter the vial so that the medication will flow freely. In order to maintain a pressure equilibrium, during the extraction of a liquid medication from a vial ambient air may to enter the vial, while during the addition of a liquid to dilute or reconstitute a medication pressurized air within the vial is released.
In the medical field, various types of medicinal fluids are reconstituted or mixed with a diluent before being delivered intravenously to a patient. With the use of commonly known delivery devices (e.g., a syringe and a vented cannula assembly), the diluent is injected into a vial containing the medicinal fluid or vice versa. Afterwards, the vial containing the mixed solution (e.g., the medicinal fluid and the diluent) is shaken to mix the medicinal fluid with the diluent. This type of fluid transfer may be repeated several times until proper mixing has been accomplished.
During reconstitution, the air within a closed medicinal vial or a closed diluent vial becomes pressurized due to the addition of fluid into the closed vial. The pressurized air is typically vented through a vent channel within a vented cannula, which is used to inject the fluid from one vial into the other vial. When this occurs, aerosolized contaminants of the medicinal fluid (e.g., chemotherapy drugs) may be vented from the vented cannula and into the air surrounding a user. Exposure to such aerosolized contaminants may be harmful to the user preparing such medicinal solutions. Accordingly, a continuing need exists in the art for a vented cannula assembly which prevents aerosolized contaminants from being expelled from a vial during reconstitution or a like procedure.
Similarly, during repeated extraction of a medication from a single vial, ambient air enters the vial and may contaminate the contents of the vial. Accordingly, it is desirable to filter ambient air prior to entering the vial.